--*t 格式为一个表 
t = os.date("*t")
t1 = os.date("%Y/%m/%d",os.time(t))
print(t1)
t.day = t.day + 40
t2 = os.date("%Y/%m/%d",os.time(t));
print(t2)
local t5_3 = os.time{year=2015,month=1,day=12}
local t5_2 = os.time{year=2011,month=12,day=15}
local d = os.difftime(t5_3,t5_2)
print(d // (24 * 3600))
print(os.clock())